1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
|
// Copyright 2019 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package aessiv
import (
"fmt"
"io"
"google.golang.org/protobuf/proto"
"github.com/tink-crypto/tink-go/v2/core/registry"
"github.com/tink-crypto/tink-go/v2/daead/subtle"
"github.com/tink-crypto/tink-go/v2/internal/internalapi"
"github.com/tink-crypto/tink-go/v2/internal/protoserialization"
"github.com/tink-crypto/tink-go/v2/keyset"
"github.com/tink-crypto/tink-go/v2/subtle/random"
aspb "github.com/tink-crypto/tink-go/v2/proto/aes_siv_go_proto"
tinkpb "github.com/tink-crypto/tink-go/v2/proto/tink_go_proto"
)
const (
keyVersion = 0
keyTypeURL = "type.googleapis.com/google.crypto.tink.AesSivKey"
)
// keyManager generates AES-SIV keys and produces instances of AES-SIV.
type keyManager struct{}
var _ registry.KeyManager = (*keyManager)(nil)
// Primitive constructs an AES-SIV for the given serialized [aspb.AesSivKey].
func (km *keyManager) Primitive(serializedKey []byte) (any, error) {
if len(serializedKey) == 0 {
return nil, fmt.Errorf("aes_siv_key_manager: empty key")
}
// This method returns a primitive without prefix, thus we set the output
// prefix type to RAW.
keySerialization, err := protoserialization.NewKeySerialization(&tinkpb.KeyData{
TypeUrl: typeURL,
Value: serializedKey,
KeyMaterialType: tinkpb.KeyData_SYMMETRIC,
}, tinkpb.OutputPrefixType_RAW, 0)
if err != nil {
return nil, err
}
key, err := protoserialization.ParseKey(keySerialization)
if err != nil {
return nil, err
}
aesSIVKey, ok := key.(*Key)
if !ok {
return nil, fmt.Errorf("aes_siv_key_manager: invalid key type: got %T, want %T", key, (*Key)(nil))
}
ret, err := NewDeterministicAEAD(aesSIVKey, internalapi.Token{})
if err != nil {
return nil, fmt.Errorf("aes_siv_key_manager: %v", err)
}
return ret, nil
}
// NewKey generates a new [aspb.AesSivKey]. serializedKeyFormat is optional
// because there is only one valid key format.
func (km *keyManager) NewKey(serializedKeyFormat []byte) (proto.Message, error) {
// A nil serializedKeyFormat is acceptable. If specified, validate.
if serializedKeyFormat != nil {
keyFormat := new(aspb.AesSivKeyFormat)
if err := proto.Unmarshal(serializedKeyFormat, keyFormat); err != nil {
return nil, fmt.Errorf("aes_siv_key_manager: %v", err)
}
if keyFormat.KeySize != subtle.AESSIVKeySize {
return nil, fmt.Errorf("aes_siv_key_manager: key size != %d", subtle.AESSIVKeySize)
}
}
return &aspb.AesSivKey{
Version: keyVersion,
KeyValue: random.GetRandomBytes(subtle.AESSIVKeySize),
}, nil
}
// NewKeyData generates a new KeyData. serializedKeyFormat is optional because
// there is only one valid key format. This should be used solely by the key
// management API.
func (km *keyManager) NewKeyData(serializedKeyFormat []byte) (*tinkpb.KeyData, error) {
key, err := km.NewKey(serializedKeyFormat)
if err != nil {
return nil, err
}
serializedKey, err := proto.Marshal(key)
if err != nil {
return nil, fmt.Errorf("aes_siv_key_manager: %v", err)
}
return &tinkpb.KeyData{
TypeUrl: keyTypeURL,
Value: serializedKey,
KeyMaterialType: km.KeyMaterialType(),
}, nil
}
// DoesSupport checks whether this key manager supports the given key type.
func (km *keyManager) DoesSupport(typeURL string) bool {
return typeURL == keyTypeURL
}
// TypeURL returns the type URL of keys managed by this key manager.
func (km *keyManager) TypeURL() string { return keyTypeURL }
// KeyMaterialType returns the key material type of this key manager.
func (km *keyManager) KeyMaterialType() tinkpb.KeyData_KeyMaterialType {
return tinkpb.KeyData_SYMMETRIC
}
// DeriveKey derives a new [aspb.AesSivKey] from serializedKeyFormat and
// pseudorandomness.
//
// Unlike NewKey, DeriveKey validates serializedKeyFormat.
func (km *keyManager) DeriveKey(serializedKeyFormat []byte, pseudorandomness io.Reader) (proto.Message, error) {
keyFormat := new(aspb.AesSivKeyFormat)
if err := proto.Unmarshal(serializedKeyFormat, keyFormat); err != nil {
return nil, fmt.Errorf("aes_siv_key_manager: %v", err)
}
if keyFormat.GetKeySize() != subtle.AESSIVKeySize {
return nil, fmt.Errorf("aes_siv_key_manager: key size != %d", subtle.AESSIVKeySize)
}
if err := keyset.ValidateKeyVersion(keyFormat.GetVersion(), keyVersion); err != nil {
return nil, fmt.Errorf("aes_siv_key_manager: invalid key version: %s", err)
}
keyValue := make([]byte, subtle.AESSIVKeySize)
if _, err := io.ReadFull(pseudorandomness, keyValue); err != nil {
return nil, fmt.Errorf("aes_siv_key_manager: not enough pseudorandomness given")
}
return &aspb.AesSivKey{
Version: keyVersion,
KeyValue: keyValue,
}, nil
}
// validateKey validates the given AesSivKey.
func (km *keyManager) validateKey(key *aspb.AesSivKey) error {
err := keyset.ValidateKeyVersion(key.Version, keyVersion)
if err != nil {
return fmt.Errorf("aes_siv_key_manager: %v", err)
}
keySize := uint32(len(key.KeyValue))
if keySize != subtle.AESSIVKeySize {
return fmt.Errorf("aes_siv_key_manager: key size != %d", subtle.AESSIVKeySize)
}
return nil
}
|
